Effects of Quartz Powder on the Microstructure and Key Properties of Cement Paste

This paper compares the effects of the water-to-binder (w/b) ratio and quartz contents on the properties of cement–quartz paste. The w/b ratios of the paste mixtures specimens are 0.5 and 0.2, and the quartz powder contents are 0, 10, and 20%. At the age of 1, 3, 7, and 28 days, compressive strength test, X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), isothermal calorimetry, and thermogravimetric (TG) analysis were performed. The experimental results show that the quartz powder mainly has the dilution effect and crystal nucleation effect on cement hydration, and the addition of quartz powder does not change the type of hydration product. The effect of quartz powder on cement hydration is closely related to the w/b ratio. In the case of a low w/b ratio of 0.2, the addition of quartz powder did not impair the compressive strength of paste. For different w/b ratios (0.5 and 0.2) and various quartz powder contents (0, 10, and 20%) at different ages (1, 3, 7, and 28 days), there is a uniform linear relationship between strength and porosity. Similarly, there is a uniform linear relationship between chemically bound water and calcium hydroxide, between heat of hydration and compressive strength, and between chemically bound water and compressive strength. At the same time, the effect of the partial replacement of cement by quartz powder on sustainability is considered in this paper